diff --git a/src/lib/opds.client.ts b/src/lib/opds.client.ts
index db538c0..e82da71 100644
--- a/src/lib/opds.client.ts
+++ b/src/lib/opds.client.ts
@@ -111,9 +111,28 @@ function isNavigationLink(link: ParsedFeedLink): boolean {
   return isNavigationRel(link.rel) || type.includes('kind=navigation') || (type.includes('opds-catalog') && !isAcquisitionRel(link.rel));
 }
 
+function isCoverRel(rel?: string): boolean {
+  if (!rel) return false;
+  const normalized = rel.toLowerCase();
+  return normalized.includes('opds-spec.org/cover')
+    || normalized.includes('opds-spec.org/image')
+    || normalized.includes('image/thumbnail')
+    || normalized === 'thumbnail'
+    || normalized === 'cover';
+}
+
+function isImageType(type?: string): boolean {
+  return !!type && type.toLowerCase().startsWith('image/');
+}
+
 function pickCoverLink(links: ParsedFeedLink[]): string | undefined {
-  const cover = links.find((link) => link.rel?.includes('image/thumbnail'))
-    || links.find((link) => link.rel?.includes('image'));
+  const thumbnail = links.find((link) => {
+    const rel = (link.rel || '').toLowerCase();
+    return rel.includes('thumbnail') && (isCoverRel(link.rel) || isImageType(link.type));
+  });
+  const cover = thumbnail
+    || links.find((link) => isCoverRel(link.rel))
+    || links.find((link) => isImageType(link.type) && !isAcquisitionRel(link.rel));
   return cover?.href;
 }